With the development of Internet Protocol (IP) in future networks and services, various technologies of performing clock synchronization and time synchronization on the IP network are also developed rapidly. In various packet clock technologies, 1588V2 protocol of Institute of Electrical and Electronics Engineers (IEEE) has been gradually adopted in telecommunication-level communication devices due to the capability of providing time synchronization in the precision of microsecond level. The 1588V2 protocol implements time synchronization between network elements at both sides of a communication link by transferring a 1588V2 message on the single communication link, and if the communication link is interrupted, the 1588V2 protocol is switched to another normal communication link through a source selection method, so as to keep the time synchronization. However, during the switch of the communication link, a system tracking clock is lost, and therefore, a system clock is in a retention stage. In a wired connection system, such as an optical fiber system or an Ethernet cable system, the switch of a communication link will not occur frequently, and therefore, the system clock being in the retention stage for a short time does not influence recovery of time. Moreover, in the conventional wireless communication system, the protection switch of the communication link occurs frequently due to instability of a communication channel and rapid fading of the communication channel caused by multi-path interference, and therefore, through a Hitless Switch Module (HSM), data services of the communication link may ensure that the services do not have any error code and ensure that quality of service has no harm.
During the implementation of the present invention, the inventor finds that the prior art at least has the following disadvantage: sending time points of the same message on a main link and a backup link are hard to be the same in the wireless communication system, so that receiving time points of the same message are not the same.